This invention relates generally to a new and improved cuvette, relates particularly to a new and improved combination of cuvette and lancet, and still more particularly relates to a new and improved cuvette of optically tranparent material of a shape and provided with optical elements such as integrally formed optical elements for causing a beam of light to pass therethrough by total internal reflectance and for causing the beam of light to be reflected back along a line different from the direction of the line of entry into the cuvette such as back along a line generally parallel to the line of entry of the beam of light into the cuvette and in the opposite direction of the direction of entry of the beam of light into the cuvette.
The prior art, as well known to those skilled therein, is replete with a multitude of different cuvettes of different sizes and shapes, of different materials, and for many different purposes. Included in such prior art cuvettes are cuvettes of optically transparent material for receiving an optically transparent medium including a reagent test system and which in the presence of an analyte reacts with the analyte to cause a change in at least one optical transmissive property or characteristic of the medium such as a change in color, turbidity, light absorption, etc.; typically, after the reaction, a beam of light (sometimes referred to in the art as an analytical light beam) transmitted through the medium is measured and compared with the measurement of a beam of light transmitted previously through the medium prior to the reaction, the light beams are compared and a determination of the analyte, or a characteristic thereof, made, e.g. determination of a substance found in body fluids such as the level of extra cellular (serum) glucose in blood.
While various prior art optically transmissive or transparent cuvettes function well for their intended purpose, there exists a need for a new and improved optically transparent or transmissive cuvette for causing a light beam to pass therethrough, and through a medium contained therein and undergoing (or having undergone) a change in optical transmissive characteristic, by total internal reflectance; total internal reflectance provides the light beam with a long path (as distinguished from the path of a light beam passing straight therethrough) providing averaging of the reaction occurring at different regions of the medium which in turn enhances analyte determination.
In addition, there exists a need for an optically transmissive transparent cuvette which causes the beam of light passing therethrough to be reflected back along a line generally parallel to the line of entry of the beam of light into the cuvette and in the opposite direction of the entry of the beam of light into the cuvette. This parallel reversal in direction permits the light beam source and light beam detector to be mounted parallel and directed in the same direction towards the cuvette which is desirable in many applications such as, for example, the one taught in U.S. patent application Ser. No. 888,754, entitled OPTICAL ANALYZER, filed July 22, 1986, Peter M. Meserol et al. inventors, and assigned to the same assignee as the present invention.
As noted by way of example above, a body fluid such as blood, or a sample portion thereof, is often the analyte of interest to be reacted with a reagent system in the cuvette to perform analyte determination such as the determination of the amount of blood extra cellular (serum) glucose present in the blood. Such blood is typically produced by puncturing the skin of a person. In the prior art, the lancet and cuvette are typically physically separate objects thereby making it somewhat tedious or at least difficult to first puncture the human skin with a lancet, dispose of the lancet, and thereafter transfer the blood to a test object such as a bibulous test strip. Accordingly, there exists a need in the art for the combination of a cuvette and lancet to facilitate skin puncture with resulting production of a body fluid of interest such as blood for ready transfer to a physically associated cuvette for analysis or determination of the body fluid.